Police officer Aleksandr Kotin is trying to establish identity of a patient of psychiatric hospital who sometimes suffers from amnesia. After checking this man’s residence place the officer finds out that a man who used to live there is considered to be dead. When going further into investigation process he discovers even more enigmatic story of disappearance of a hundred of people who took an underground train and did not come back to the surface. At his own risk he begins investigating this disappearance case which is connected with a state top secret story…